Glass mat and method of making the glass mat

ABSTRACT

A method of making a glass mat includes providing an assembly of glass fibers, applying a binder composition to the assembly of glass fibers, wherein the binder includes an organic resin, and curing the binder composition while dimensionally constraining the assembly of glass fibers. Dimensional constraining includes directly contacting a first major surface and a second major surface of the assembly of glass fibers between two substantially parallel surfaces. Further provided is a glass mat that includes an assembly of glass fibers, wherein the assembly of glass fibers are substantially randomly oriented with a tensile anisotropy of less than about 6 in any two directions. The glass mat has a decreased surface roughness and a decreased caliper compared to an equivalent glass mat having an assembly of naturally packed glass fibers with an equivalent fiber diameter size.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of and claims priority under 35 U.S.C.§ 120 to U.S. patent application Ser. No. 15/199,266, entitled “A GLASSMAT AND METHOD OF MAKING THE GLASS MAT”, by Jeffrey H. PEET et al.,filed Jun. 30, 2016, which claims priority under 35 U.S.C. § 119(e) toU.S. Provisional Application No. 62/187,012, entitled “A GLASS MAT ANDMETHOD OF MAKING THE GLASS MAT”, by Jeffrey H. PEET et al., filed Jun.30, 2015, both of which are assigned to the current assignee hereof andincorporated herein by reference in their entireties.

FIELD OF THE DISCLOSURE

The present disclosure relates to a glass mat and in particular, a glassmat for construction products.

BACKGROUND

Building materials for construction, such as gypsum wall boards, cementboards, tiles, and roofing shingles, are typically constructed with aglass fiber mat. Chopped strand mat, suitable for use in constructionmaterials, generally includes glass fibers because they are of highstrength and tend not to shrink during use. The glass fibers aretypically formed by attenuating streams of molten glass material from abushing. The fibers are drawn from the bushing and the fibers are thenchopped directly into a container. The chopped fibers are then dispersedin a water slurry which contains surfactants, viscosity modifiers,dispersants and other chemical agents. The fibers and slurry areagitated to disperse the fibers prior to depositing the mixture onto amoving screen where most of the water is removed. Although thisgenerally describes a wet-laid process, a dry-laid process may be used.A polymeric binder is then applied. After application of the polymericbinder, the resulting mat is heated to remove the remaining water andcure the binder.

Important properties for a glass mat include surface roughness, caliper,tensile strength, and tear strength. These properties are useful indetermining the efficacy of the manufacture of glass mat products andfinal properties of the glass mat. Modifications to the glass mats toimprove such properties are desired.

Accordingly, a need continues to exist in the art for improved processesfor manufacturing glass mats that can lower product cost and meet theneeds of new and demanding applications.

SUMMARY

In an embodiment, a method of making a glass mat includes providing anassembly of glass fibers; applying a binder composition to the assemblyof glass fibers, wherein the binder includes an organic resin; andcuring the binder composition while dimensionally constraining theassembly of glass fibers, wherein dimensional constraining includesdirectly contacting a first major surface and a second major surface ofthe assembly of glass fibers between two substantially parallelsurfaces.

In another embodiment, a glass mat includes an assembly of glass fibers,wherein the assembly of glass fibers are substantially randomly orientedwith a tensile anisotropy of less than about 6 in any two directions;and a binder composition including an organic resin; wherein the glassmat has a surface roughness more than about 10% lower than an equivalentglass mat having an assembly of naturally packed glass fibers with anequivalent fiber diameter size.

In yet another embodiment, a glass mat includes an assembly of glassfibers, wherein the assembly of glass fibers are substantially randomlyoriented with a tensile anisotropy of less than about 6 in any twodirections; and a binder composition including an organic resin; whereinthe glass mat has a caliper more than about 10% lower than an equivalentglass mat having an assembly of naturally packed glass fibers with anequivalent fiber diameter size.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are illustrated by way of example and are not limited in theaccompanying figures.

FIG. 1 includes a cross-sectional view of a portion of a glass matduring cure under dimensional constraint illustrated in accordance withan embodiment described herein.

FIG. 2 is a plot of the surface profile of a glass mat cured withoutdimensional constraint.

FIG. 3 is a plot of the surface profile of a glass mat cured withdimensional constraint.

FIG. 4 is a plot of Pp (maximum height of the summits, i.e. heightbetween the highest peak and the mean plane) for a number of exemplaryglass mats cured with and without dimensional constraint.

FIG. 5 is a plot of Pz (ten point height of the surface, i.e. the meandistance between the 5 highest peaks and 5 deepest holes) for a numberof exemplary glass mats cured with and without dimensional constraint.

FIG. 6 is a plot of RMS (root-mean-square deviation of the surface, i.e.the efficient value for the amplitudes of the surface) for a number ofexemplary glass mats cured with and without dimensional constraint.

FIG. 7 is a plot of caliper for a number of exemplary glass mats curedwith and without dimensional constraint.

FIG. 8 is a plot of mat Elmendorf tear strength for a number ofexemplary glass mats cured with and without dimensional constraint.

FIG. 9 is a plot of tensile strength for a number of exemplary glassmats cured with and without dimensional constraint.

FIG. 10 is a plot of surface smoothness of exemplary mats cured with andwithout dimensional constraint.

FIG. 11 is a plot of caliper of exemplary mats cured and pressed undervarying conditions.

FIG. 12 is a plot of tensile strength of exemplary mats cured andpressed under varying conditions.

FIG. 13 is a plot of RMS roughness of exemplary mats cured and pressedunder varying conditions.

FIG. 14 is a plot of Pp flatness of exemplary mats cured and pressedunder varying conditions.

FIG. 15 is a plot of Pz flatness of exemplary mats cured and pressedunder varying conditions.

FIG. 16 is a plot of caliper of exemplary mats heated at varioustemperatures.

Skilled artisans appreciate that elements in the figures are illustratedfor simplicity and clarity and have not necessarily been drawn to scale.For example, the dimensions of some of the elements in the figures maybe exaggerated relative to other elements to help to improveunderstanding of embodiments of the invention.

DETAILED DESCRIPTION

The following description in combination with the figures is provided toassist in understanding the teachings disclosed herein. The followingdiscussion will focus on specific implementations and embodiments of theteachings. This focus is provided to assist in describing the teachingsand should not be interpreted as a limitation on the scope orapplicability of the teachings. However, other teachings can certainlybe used in this application.

As used herein, the terms “comprises”, “comprising”, “includes”,“including”, “has”, “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a method,article, or apparatus that comprises a list of features is notnecessarily limited only to those features but may include otherfeatures not expressly listed or inherent to such method, article, orapparatus. Further, unless expressly stated to the contrary, “or” refersto an inclusive-or and not to an exclusive-or. For example, a conditionA or B is satisfied by any one of the following: A is true (or present)and B is false (or not present), A is false (or not present) and B istrue (or present), and both A and B are true (or present).

Also, the use of “a” or “an” is employed to describe elements andcomponents described herein. This is done merely for convenience and togive a general sense of the scope of the invention. This descriptionshould be read to include one or at least one and the singular alsoincludes the plural, or vice versa, unless it is clear that it is meantotherwise. For example, when a single item is described herein, morethan one item may be used in place of a single item. Similarly, wheremore than one item is described herein, a single item may be substitutedfor that more than one item.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. The materials, methods, andexamples are illustrative only and not intended to be limiting. To theextent not described herein, many details regarding specific materialsand processing acts are conventional and may be found in reference booksand other sources within the structural arts and correspondingmanufacturing arts.

In an embodiment, the present invention provides a glass mat. The glassmat includes an assembly of glass fibers; and a binder compositionincluding an organic resin. The glass mat is formed by a method thatincludes curing the binder while the mat and the binder are under adimensional constraint. Like a glass mat formed absent any dimensionalconstraint, the glass mat when cured under dimensional constraint hassubstantially randomly oriented glass fibers having a tensile anisotropyof less than about 6 in any two directions. In an embodiment, the glassmat has a decreased surface roughness compared to an equivalent glassmat having an assembly of naturally packed glass fibers with anequivalent fiber diameter size. In a further embodiment, the glass mathas a decreased caliper compared to an equivalent glass mat having anassembly of naturally packed glass fibers with an equivalent fiberdiameter size.

In a particular example, the glass mat is advantageously produced bycuring the binder composition of the glass mat while the assembly ofglass fibers is under dimensional constraint. In an embodiment, anydimensional constraint is envisioned that constrains and preventsexpansion of the assembly of glass fibers and binder composition duringcure. This is in contrast to a glass mat having an assembly of naturallypacked glass fibers. As used herein, “naturally packed glass fibers”include an assembly of glass fibers and a binder composition wherein thebinder composition is not cured under dimensional constraint. Withoutdimensional constraint applied to the glass mat during cure, thethickness, length, width, or combination thereof of the glass mat willexpand during the cure of the binder. In particular, the cure of thebinder creates voids within the binder which bridges the glass fiberswithin the mat, causing the glass mat to expand resulting in naturallypacked glass fibers. Although not being bound by theory, the voids canbe created by moisture released during the curing reaction and/orboiling off of the solvent during cure. However, when the assembly ofglass fibers is cured under dimensional constraint, the assembly ofglass fibers is prevented from expanding. In a particular embodiment,the assembly of glass fibers is prevented from expanded in the verticaldirection. With the use of dimensional constraint, the expansion of theglass mat is prevented such that the glass mat has a reduced caliper,such as more than about 10% lower, more than about 20% lower, or even30% lower, compared to an equivalent glass mat having an assembly ofnaturally packed glass fibers with an equivalent fiber diameter size.Additionally, even though a lower caliper is achieved by curing thebinder of the glass mat under dimensional constraint, any caliper lessthan that of the naturally packed glass mat is envisioned. Typically,the glass mat can have any caliper desired. In an example, the caliperis at least about 5 mil, such as about 5 mil to about 200 mil, such asabout 10 mil to about 75 mil, such as about 10 mil to about 40 mil, suchas about 10 mil to about 30 mil, such as about 10 mil to about 25 mil.In an example, the caliper of the glass mat is not greater than about200 mil, such as not greater than about 100 mil, such as not greaterthan 50 mil. Due to the brittle nature of both glass fibers and curedbinder, it is surprising that a glass mat can be constrained withsufficient pressure during cure to prevent expansion without damagingthe glass fibers and thereby reducing glass strength.

In addition to reduced caliper, the glass mat cured while subjected todimensional constraint has substantially randomly oriented glass fibershaving a tensile anisotropy of less than about 6 in any two directions,such as about 1 to about 4, such as about 1.1 to about 4, such as about1.2 to about 4. In an embodiment, the two directions are the machinedirection and the cross direction, which is substantially perpendicularto the machine direction. “Tensile anisotropy” as used herein refers tothe ratio of the tensile strength of the glass mat taken in any twodirections. In the case of a typical wet laid glass mat, with or withoutdimensional constraint, the tensile anisotropy will be highest whencomparing the machine direction and the cross direction. In otherassemblies of glass fibers, the maximum anisotropy may be found whencomparing different directions. In comparison, an equivalent glass mathaving an assembly of perfectly randomly oriented glass fibers wouldhave a tensile anisotropy of about 1 in any two directions. As such, theperfectly randomly oriented glass mat would have tensile isotropy, whichimplies a generally random direction of the assembly of glass fibers,i.e. with no structural order of the fibers.

In particular, curing under dimensional constraint provides anadvantageous surface roughness of the glass mat. Due to the cure underdimensional constraint, the glass mat has a decreased surface roughness,such as less than about 10%, such as less than about 20%, or even lessthan about 30%, compared to an equivalent glass mat having an assemblyof naturally packed glass fibers with an equivalent fiber diameter size.Unexpectedly, curing the glass mat under dimensional constraint not onlyprovides smoothness on the surface of the glass mat but also does notsubstantially damage the glass fibers. “Substantial damage” as usedherein refers to breakage of at least 20% of the glass fibers, resultingin a reduction in the tensile properties of the glass mat.

In another embodiment, a glass mat having an assembly of glass fiberswith a larger micron fiber diameter size cured under dimensionalconstraint can be obtained with a surface roughness equivalent or lessthan a glass mat with an assembly of glass fibers having a smallermicron fiber diameter size cured without dimensional constraint. Withconventional cure, desirable smoothness of the glass mat having anassembly of naturally packed glass fibers was achieved by decreasing thediameter of the glass fibers. However, dimensional constraint provides adecreased surface roughness for fibers of greater diameter size notbefore achieved with conventional cure.

In an embodiment, glass fibers having a diameter of about 11 microns,such about 13 microns, or even about 16 microns used in a glass matdimensionally constrained during cure provides a glass mat with asurface roughness (Sq) of less than about 200 μm (root mean square ofthe surface area in microns), such as less than about 140 μm, or evenless than about 120 μm for a 16 micron diameter assembly of glassfibers.

Furthermore, dimensional constraint during cure provides a glass matwith a uniform thickness across a total width of the glass mat. Forinstance, the thickness of the mat varies not greater than about 10%over the total width of the glass mat. In an embodiment, the Pz value isnot greater than 1000 um, such as not greater than 800 um, such as notgreater than 700 um, or even not greater than 600 um when measured via aNanovea 3D Optical Surface Profilometer using a white light chromaticaberration technique with 7.5 centimeter line scan in any particulardirection. Accordingly, the glass mat has a flatness that is desirable,especially for construction applications where a uniform mat is desired.In comparison, an assembly of naturally packed glass fibers not curedunder dimensional constraint may have a thickness that varies across thetotal width of the glass mat by at least 15%. In a further embodiment,the glass mat has a higher packing density, such as greater than about30%, such as 40%, or even 50%, compared to a glass mat having theassembly of naturally packed glass fibers with equivalent fiber diametersize that are not cured under dimensional constraint.

Prior to the cure of the glass mat, an exemplary method of forming aglass fiber mat in accordance with the present invention begins with anassembly of fibers, such as chopped bundles of glass fibers of suitablelength. In a particular embodiment, the assembly of fibers can be anylength such as continuous strand, chopped, or combination thereof. In amore particular embodiment, the assembly of fibers is chopped into asuitable length to provide randomly disposed fibers. Any reasonablelength of fibers is envisioned. Any reasonable diameter of the fibers isenvisioned. Generally, fibers having a length of about 0.5 inches toabout 3 inches and a diameter of at least about 3 microns, such as about3 microns to about 30 microns, such as about 3 microns to 20 microns,such as at least about 11 microns, such as about 13 microns, or even 16microns are used. In a particular embodiment, the fibers have a diameterof about 11 microns to about 16 microns. Each assembly may contain anyreasonable amount of fibers. The assembly of fibers can include avariety of suitable materials. For instance, the assembly of fibers caninclude a glass fiber, such as a fiber made from A-type glass fiber, aC-type glass fiber, an E-type glass fiber, an S-type glass fiber, anE-CR-type glass fiber, a wool glass fiber, a synthetic fiber, a naturalfiber, or a combination thereof. Any suitable configuration of theassembly of fibers is envisioned. In an embodiment, the assembly offibers may be in a non-woven mat.

An exemplary method of making the glass mat includes providing theassembly of glass fibers. Typically, the assembly of fibers is added toa dispersant medium to form an aqueous slurry, known in the art as“white water”. The white water typically contains glass, dispersant(s),viscosity modifier(s), foam control and biocide additives. The fibrousslurry is then agitated to form a workable, uniform dispersion of glassfiber having a suitable consistency. The dispersant may containpolyacrylamide, hydroxyethyl cellulose, and other additive such assurfactants, lubricants, defoamers, the like, or combinations thereof.

The fiber and white water dispersion is then passed onto a mat-formingmachine containing a mat forming screen. The dispersion is usuallydiluted with water to a lower fiber concentration prior to beingdispersed on a screen. The fibers are collected at the screen in theform of a wet fiber mat, and the excess water is removed by gravity or,more preferably, by vacuum in a conventional manner, such as by vacuumboxes. Although this generally describes a wet-laid process, a dry-laidprocess may also be envisioned. For instance, with a dry-laid process,fibers may be spun from a bushing directly onto a moving web. The bindercomposition is subsequently applied.

The binder composition is used to fixedly bond the assembly of fibers.The binder composition is traditionally applied to the gravity- orvacuum-assisted de-watered white glass mat. Application of the bindercomposition may be accomplished by any conventional means, such as bysoaking the mat in an excess of binder solution, or by coating the matsurface by means of a binder applicator such as a sprayer, roll, orcurtain. The components of the binder composition may be appliedseparately or mixed together by any method envisioned. For instance, ifapplied separately, the components of the binder composition may beadded by the same or a different method. In an embodiment, any othersequence of adding the components of the binder composition isenvisioned. The total concentration of components in the bindercomposition in an aqueous solution can vary widely in accordance withthe practice of the present invention. Any amount of binder compositionis envisioned but it will usually be found convenient and satisfactoryto make up this composition in the range from about 5% by weight toabout 50% by weight, such as about 10% by weight to about 40% by weight,such as about 10% by weight to about 30% by weight of the cured glassmat.

The binder composition includes any suitable organic resin. The organicresin can include one or more suitable monomers, oligomers, polymers,copolymers, a suitable blend, or combination thereof. In a particularembodiment, the organic resin is any reasonable resin envisioned forglass mat applications. In an embodiment, the organic resin comprisesone or several of a urea-formaldehyde composition, a latex composition,an acrylic composition, a styrene-butadiene rubber (SBR) composition, avinyl acetate ethylene composition, a blend or combination thereof. In aparticular embodiment, the organic resin comprises a urea-formaldehydecomposition, a latex composition, or combination thereof. In anembodiment, the latex is present at an amount of up to about 5% byweight, such as up to about 7% by weight, or even up to about 100% byweight, based on the total weight % of the binder composition.

The binder composition may also contain a variety of other knownadditives such as an adhesion promoter to enhance the adhesion of thebinder composition to the glass mat to increase the bonding strengthbetween the assembly of fibers, a silica colloid to enhance fireresistance, antifoamers, biocides, pigments, the like, or combinationsthereof. In an embodiment, the binder composition can include less thanabout 25% by weight of additives, based on the total weight of thebinder composition. In another embodiment, the binder composition issubstantially free of additives. “Substantially free” as used hereinrefers to less than about 1% by weight of additives, less than about0.5% by weight of additives, or even less than about 0.1% by weight ofadditives, based on the total weight of the binder composition.

Following application of the binder composition, the glass fiber mat isde-watered by any reasonable means, such as under vacuum, to removeexcess binder solution. In an embodiment, the mat is dried prior tocure. Any method of drying the glass mat is envisioned. In a particularembodiment, the drying is at a temperature wherein the glass mat doesnot reach the cure temperature of the binder and is dependent upon thebinder chosen. For instance, drying is with forced heated air, such as aconvection oven, a gas fired oven, an infrared heater, a heated drum, orcombination thereof. In an exemplary embodiment, at least about 95%,such as at least about 90%, or even at least about 80% of water weightof the aqueous binder is removed during the drying process. In anembodiment, the binder is partially cured during the drying step, with acure of not greater than a 50%, as measured by a ratio of dry tensilestrength to tensile strength of a wet glass mat subjected to 10 minutesexposure to 80° C. hot water.

The glass mat is subjected to final curing of the binder underdimensional constraint. Any method of applying the dimensionalconstraint is envisioned, such as two substantially parallel surfaces.For instance, a first major surface and a second major surface of theglass mat are in directly in contact with two substantially parallelsurfaces. The substantially parallel surfaces may be in any geometricconfiguration envisioned, such as flat, round, or combination thereof.In an embodiment, the glass mat is placed between at least one metalsurface, at least one fabric belt, or combination thereof. In analternate embodiment, the mat could be constrained between a flatsurface, such as a metal plate, and an open surface, such as a wovenbelt. In a further alternate embodiment, at least one of thesubstantially parallel surfaces could be patterned to impart a specificdesirable texture on the cured mat. In a particular embodiment, theconstraining material has a desirable thermal conductivity, such asgreater than about 10 W/m·K. In a particular embodiment, the thermalconductivity is desirable to heat the constraining material, such as atleast one of the substantially parallel surfaces, or even bothsubstantially parallel surfaces, to a temperature sufficient to heat themat and cure the binder composition. In an even more particularembodiment, the constraining material is at least one metal plate havinga thermal conductivity greater than about 10 W/m·K. In an exemplaryembodiment, the glass mat is dimensionally constrained by substantiallyparallel surfaces on a rotocure, a conveyor belt, i.e. flat bed, orcombination thereof. In an embodiment, a pressure is applied to the matduring dimensional constraint. In a more particular embodiment, thepressure is at least about 0.01 psi (pounds per square inch), such as atleast about 0.02 psi, such as at least about 0.03 psi, such as at leastabout 0.04 psi, such as at least about 0.05 psi, such as at least about1.0 psi, such as at least about 5.0 psi, or even greater, with theproviso that the pressure does not substantially damage the glassfibers.

Turning to FIG. 1, a cross-sectional view of a portion of a glass mat100 is illustrated under dimensional constraint during cure inaccordance with an embodiment described herein. The glass mat 100includes an assembly of filaments 110 where the assembly of filaments110 includes a binder composition thereon (not shown). Further includedare substantially parallel metal plates 120 and 130 in direct contactwith a first major surface 140 and a second major surface 150 of theglass mat 100. The distance between the substantially parallel metalplates 120 and 130 is represented by “D”. Any distance is envisioned andis dependent upon the final thickness desired for the glass mat.Specifically, the thickness of the cured glass mat is substantiallyequal to the distance between the substantially parallel metal plates.In a particular embodiment, the dimensional constraint has a distancebetween the substantially parallel surfaces less than or equal to athickness of a naturally cured glass mat.

In an embodiment, the cure of the binder is facilitated with heatprovided by any reasonable means. Although cure is described by heatingat least one parallel surface, such as a metal plate, to a temperatureto heat the mat and cure the binder, any other methods of providing heatare also envisioned such as, for example, infrared heating. Anyreasonable time and temperatures is envisioned and is dependent upon thebinder composition and the desired process speed. In an embodiment, heattreatment is sufficient to effect curing. In an embodiment, catalyticcuring may also be used. Dimensional constraint of the glass mat andcure of the binder occurs concurrently and may be provided by the sameor different means. Although described as substantially parallel metalplates, any other configuration of the dimensional constraint may beenvisioned.

The glass mat as described has advantageous and unexpected properties.In addition to the aforementioned surface roughness, caliper, anduniformity, the glass mat of the present invention has desirableproperties such as tensile strength and tear strength compared to anequivalent glass mat having an assembly of naturally packed glass fiberswith an equivalent fiber diameter size. For instance, the glass mat hasdesirable tensile strength such as a dry tensile strength of about 100N/inch to about 200 N/inch, such as about 100 N/inch to about 180N/inch, or even about 100 N/inch to about 160 N/inch.

Due to the constraining of the fibers, the mat produced from constrainedcuring can also have improved handling properties. The itchy feelingoften perceived by users of glass fabrics can be reduced by the use ofthe constrained curing process due to reduction of fiber ends pointingperpendicular to the surface of the mat.

The glass mat as described above can be provided in any suitable mannerto provide for a construction product. Any construction product isenvisioned where low caliper, smoothness, flatness, and tensile strengthare desired. An exemplary construction product includes, for example,gypsum wall board, a cement board, a tile, and a roofing shingle.

In an embodiment, the construction product is a facer for a gypsum wallboard or a cement board. The glass mat can be provided in thecementitious product to provide structural integrity to the resultingcementitious product. The glass mat may be situated in any suitableconfiguration within the cementitious product. In an embodiment, theglass mat can be adhered, affixed, or otherwise coupled to any suitablesurface, edge, or face of an existing cementitious product. For example,the glass mat can be produced as described above and then adhered to acured cementitious product. Alternatively, the glass mat can be producedsimultaneously or concurrently while it is being coupled to acementitious product. In an embodiment, at least a portion of the glassmat can be at least partially embedded to any suitable depth from asurface or edge of the cementitious product. For example, at least aportion of the glass mat can be embedded to between about 0.01 inchesand about 0.25 inches from a surface or edge of the cementitiousproduct. “Partially embedded,” as used herein, refers to a depth withinthe cementitious product of at least about 0.01 inches. In a particularembodiment, the glass mat can be substantially embedded. “Substantiallyembedded,” as used herein, refers to a depth within the cementitiousproduct of at least about 0.05 inches. For example, the glass mat can bepartially or substantially embedded in a cementitious slurry or mixturethat is thereafter dried, hardened, or otherwise cured to provide acementitious product with the glass mat partially or substantiallyembedded to a suitable depth from a surface or edge of the cementitiousproduct. In an embodiment, the cementitous slurry substantiallyimpregnates a plurality of interstices between the assembly of fibers.In a further embodiment, a cementitious product can include any suitablenumber of glass mats as described herein. For example, a cementitiousproduct can include more than one glass mat, each of which can be atleast partially embedded to a suitable depth from opposite majorsurfaces of the cementitious product. Any cementitious slurry isenvisioned. In an embodiment, the cementitious slurry includes Portlandcement, magnesia cement, alumina cement, gypsum, blends, or combinationsthereof.

In a further embodiment, the glass mat may be coated with a polymer filmcoating. Any reasonable polymer film coating is envisioned. Typically,the polymer film coating chosen is dependent upon the final propertiesdesired for the construction product. In an embodiment, the polymer filmcoating includes a latex, an ethylene methyl acrylate, ethylene vinylacetate, polyethylene terephthalate, polyamide, hot melt adhesive,fluoropolymer, polyolefin, or combination thereof. The method ofapplying the polymer film coating is dependent upon the material. Anymethod is envisioned such as coating, extruding, spraying, orlaminating. For instance, a polymer film coating may be extrudeddirectly onto the glass mat without any intervening layers. In anotherembodiment, a polymer film coating may be laminated, with or without anadhesive, onto the glass mat.

In an example, the polymer film coating can be provided on the glass matand can be positioned on any portion of the glass mat desired. In anembodiment, the polymer film coating can partially or substantially coatat least one surface the glass mat. In an embodiment, the polymer filmcoating can partially coat at least two surfaces of the glass mat. In aparticular embodiment, the polymer film coating can substantially coatthe glass mat and can penetrate the glass mat. The polymer film coatingcan also include more than one layer on the glass mat, each of which canbe allowed to set, harden, dry, or otherwise cure before any additionallayers of polymer film coating are applied. The polymer film coating caninclude any suitable thickness such as at least about 5 microns, orrange of thicknesses, such as between about 5 microns and about 300microns.

Any one or more suitable components are envisioned for the glass matdepending upon the final product and properties desired. In anembodiment, the glass mat can include one component such as a nonwovenlaid scrim. In another embodiment, the glass mat can include more thanone component, such as one or more scrims, either woven or nonwoven,suitably coupled to one or more mats, either woven or nonwoven. Forexample, a woven scrim including glass fibers can be coupled to anonwoven mat including polymer fibers.

Many different aspects and embodiments are possible. Some of thoseaspects and embodiments are described herein. After reading thisspecification, skilled artisans will appreciate that those aspects andembodiments are only illustrative and do not limit the scope of thepresent invention. Embodiments may be in accordance with any one or moreof the embodiments as listed below.

Embodiment 1

A method of making a glass mat including providing an assembly of glassfibers; applying a binder composition to the assembly of glass fibers,wherein the binder includes an organic resin; and curing the bindercomposition while dimensionally constraining the assembly of glassfibers, wherein dimensional constraining includes directly contacting afirst major surface and a second major surface of the assembly of glassfibers between two substantially parallel surfaces.

Embodiment 2

A glass mat including an assembly of glass fibers, wherein the assemblyof glass fibers are substantially randomly oriented with a tensileanisotropy of less than about 6 in any two directions; and a bindercomposition including an organic resin; wherein the glass mat has asurface roughness more than about 10% lower than an equivalent glass mathaving an assembly of naturally packed glass fibers with an equivalentfiber diameter size.

Embodiment 3

A glass mat including an assembly of glass fibers, wherein the assemblyof glass fibers are substantially randomly oriented with a tensileanisotropy of less than about 6 in any two directions; and a bindercomposition including an organic resin; wherein the glass mat has acaliper more than about 10% lower than an equivalent glass mat having anassembly of naturally packed glass fibers with an equivalent fiberdiameter size.

Embodiment 4

The method or glass mat of any of the preceding embodiments, wherein theglass mat has a comparable tensile strength compared to an equivalentglass mat having an assembly of naturally packed glass fibers with anequivalent fiber diameter size.

Embodiment 5

The method or glass mat of any of the preceding embodiments, wherein theglass mat has a thickness that varies not greater than about 5% acrossthe total width of the mat.

Embodiment 6

The method or glass mat of embodiment 1 or 2, wherein the glass mat hasa caliper more than about 10% lower compared to an equivalent glass mathaving an assembly of naturally packed glass fibers with an equivalentfiber diameter size.

Embodiment 7

The method or glass mat of embodiment 1 or 3, wherein the glass mat hasa surface roughness more than about 10% lower compared to an equivalentglass mat having an assembly of naturally packed glass fibers with anequivalent fiber diameter size.

Embodiment 8

The method or glass mat of any of the preceding embodiments, wherein theorganic resin includes a urea-formaldehyde composition, a latexcomposition, a styrene-butadiene rubber (SBR) composition, a vinylacetate ethylene composition, a blend or combination thereof.

Embodiment 9

The method or glass mat of embodiment 8, wherein the binder compositionincludes the latex present at an amount of up to about 5% by weight,such as up to about 7% by weight, or even up to about 100% by weight,based on the total weight % of the binder composition.

Embodiment 10

The method or glass mat of any of the preceding embodiments, wherein thebinder composition is about 5% by weight to about 50% by weight of thecured glass mat.

Embodiment 11

The method or glass mat of any of the preceding embodiments, wherein theassembly of fibers is a non-woven mat.

Embodiment 12

The method or glass mat of any of the preceding embodiments, wherein theassembly of glass fibers includes an A-type glass fiber, a C-type glassfiber, an E-type glass fiber, an S-type glass fiber, an E-CR-type glassfiber, a wool glass fiber, or a combination thereof.

Embodiment 13

The method of any of the preceding embodiments, wherein the dimensionalconstraint has a distance between the substantially parallel surfacesless than or equal to a thickness of the naturally cured glass mat.

Embodiment 14

The method of any of the preceding embodiments, wherein at least one ofthe substantially parallel surfaces has a thermal conductivity of atleast about 10 W/m·K.

Embodiment 15

The method of embodiment 14, wherein curing the binder compositioncomprises heating at least one of the substantially parallel surfaces toa temperature sufficient to heat the mat and cure the bindercomposition.

Embodiment 16

The method of any of the preceding embodiments, further includingsubstantially drying the glass mat prior to cure.

Embodiment 17

The method of embodiment 16, wherein drying the glass mat is at atemperature wherein the glass mat does not reach the cure temperature ofthe binder.

Embodiment 18

The method of any of the preceding embodiments, further comprisingsubstantially embedding the glass mat in a cementitious slurry orapplying a polymer film coating to the glass mat surface.

Embodiment 19

The method of embodiment 18, wherein the cementitious slurry comprisesPortland cement, magnesia cement, alumina cement, gypsum, blends, orcombinations thereof.

Embodiment 20

The method of embodiment 18, wherein the cementitious slurrysubstantially impregnates a plurality of interstices between theassembly of fibers.

Embodiment 21

The method of embodiment 18, wherein the polymer film coating includesan ethylene methyl acrylate, ethylene vinyl acetate, polyethyleneterephthalate, polyamide, hot melt adhesive, fluoropolymer, polyolefin,or combination thereof.

Embodiment 22

The method of embodiment 18, wherein applying the polymer film includesextruding directly onto the glass mat or laminating via an adhesive.

Embodiment 23

The method of embodiment 18, wherein the glass mat is used as a facerfor a construction product.

Embodiment 24

The method of embodiment 23, wherein the construction product comprisesa gypsum wall board or a cement board.

The following examples are provided to better disclose and teachprocesses and compositions of the present invention. They are forillustrative purposes only, and it must be acknowledged that minorvariations and changes can be made without materially affecting thespirit and scope of the invention as recited in the claims that follow.

EXAMPLES Example 1

A standard urea-formaldehyde binder with 3% acrylic latex is applied toa wet laid glass mat via a wet laid process at a solid content of 15% bydilution with whitewater. The glass mats include an assembly of glassfibers having a diameter of about 16 microns. The mats are cured whileconstrained between two parallel copper plates. In order to produce matswith low caliper, the mats are dried in a convection oven at 60° C. for5 minutes prior to curing between the copper plates. Copper alloy 110was selected for its high thermal conductivity. The thermal conductivityof this alloy is 226 Btu/ft2/ft/hr/° F. or 390 W/(m*K). Each plateweighs about 5.8 pounds which puts about 0.04 psi of pressure on the matwith the plate lying on top with no additional clamping force.

A number of glass mats cured under dimensional constraint are comparedto glass mats cured without dimensional constraint. Half of the mats arefabricated between initially cool copper plates with a cure of 180° C.for 16 minutes and half were cured for 180° C. for 3 minutes without theplates. The longer cure time with the plates is to heat the plates tothe curing temperature. In addition to the samples cured with the copperplate samples being ˜30% thinner than the controls, they are also muchflatter. While the controls tend to be wavy, the copper plate samplesare smooth and uniform. Plots of the surface profiles of the samples canbe seen in FIGS. 2 and 3. FIG. 2 contains the surface profile for a matthat has been cured without dimensional constraint. FIG. 3 contains thesurface profile for a mat that has been cured under dimensionalconstraint. Clearly, the local noise and waviness of the glass mat whencured without dimensional constraint is minimized when cured underdimensional constraint.

Example 2

Several exemplary glass mats are formed and tested for roughness andflatness with cure with and without dimensional constraint as describedin Example 1. The different exemplary glass mats produced can be seen inTable 1. “h fibers” are 11 μm in diameter, “k fibers” are 13 μm indiameter, and “m fibers” are 16 μm in diameter. LOI, or loss onignition, represents the % binder in the final product by weight, andweight is the amount of glass fibers in the mat. Binder as indicated as“standard” is a 96% urea-formaldehyde (UF) binder and 85/15 is 85%acrylic binder mixed with 15% UF binder.

TABLE 1 Fiber Fiber Ex. Name LOI Weight Fiber Length amt (g) Binder 10.9 k short 20 0.9 k 0.75 3.75 Standard 2 k short 20 1.8 k 0.75 7.5Standard 3 h short 20 1.8 h 0.75 7.5 Standard 4 Short 20 1.8 m 0.75 7.5Standard 5 Control 20 1.8 m 1.25 7.5 Standard 6 85% acrylic 20 1.8 m1.25 7.5 85/15 7 100% acrylic 20 1.8 m 1.25 7.5 100% acrylic 8 15% LOI15 1.8 m 1.25 7.5 Standard 9 30% LOI 30 1.8 m 1.25 7.5 Standard

The results of Pp (maximum height of the summits, i.e. height betweenthe highest peak and the mean plane) can be seen in FIG. 4, Pz (tenpoint height of the surface, i.e. the mean distance between the 5highest peaks and 5 deepest holes) can be seen in FIG. 5, and RMS(root-mean-square deviation of the surface, i.e. the efficient value forthe amplitudes of the surface) can be seen in FIG. 6. Pp and Pz aremetrics of flatness. RMS is a metric of roughness. All measurements aredone with a Nanovea 3D Optical Surface Profilometer using a white lightchromatic aberration technique with a 7.5 centimeter line scan in anyparticular direction. Clearly, the cure under dimensional constraintsignificantly reduces roughness and increases flatness.

The results of the caliper, tear, and tensile measurements are seen inFIGS. 7, 8, and 9, respectively. The data clearly shows that the curingunder dimensional constraint reduces caliper significantly for allweights, fiber types, fiber lengths, binder compositions, and binderamounts. Caliper is reduced by about 20-30% for glass mats cured underdimensional constraint, with the exception of the binder containingacrylic. Although not being bound by theory, acrylic has less bubblingand air voids formed during cure compared to a UF binder. Accordingly,the change in caliper, although reduced, is not as significant when thebinder formulation does not contain any components which cure through acondensation reaction.

Regarding the relative performance of the mat, heavier mats have highertensile, tear, and caliper. Fiber type has little impact on caliper ortear. “h” fibers have the highest tensile with the “k” and “m” fibershaving similar tensile values. Longer fibers do not significant impactmat tensile or caliper, but do increase the tear values. High loadingsof acrylic binder increases tear and reduces tensile and caliper values.LOI increases tensile and caliper values and decreases tear values.

Overall, curing of the glass mat under dimensional constraint iseffective at high UF levels and increases the tensile of high acrylicbinders. The effect on mat tear is LOI dependent.

Example 3

Several exemplary glass mats are formed by running a roll of dried butonly partially cured mat through a rotocure process. The example isconducted using a mat specification of 1.8 lb/100 ft², 16 microndiameter fibers, and a standard urea-formaldehyde binder resin. Areduced thickness is achieved using this process without damaging theglass mat property. Table 2 below lists the physical properties ofdimensionally constrained cured glass mats made via a Rotocure incomparison to conventionally cured and prepared construction glass matproducts without dimensional constraint. The Rotocure dimensionallyconstrains the glass mat between a heated metal drum and a steel belt.It is clearly indicated in Table 2 that this process is capable ofgenerating a reduced caliper mat with the dimensionally constrainedcuring process without damaging other properties of the glass mat. It isremarkable to point out that the mat product resulted at Rotocureprocess can have a 16 mil thickness, an over 50% reduction of thicknessfrom a conventional 34 mil product that is cured without dimensionalconstraint.

TABLE 2 Constrained cured glass mat with in- specification property forroofing application Constrained Cured Trial Mat Property Summary 16Micron Glass Fiber mat Product: Specification Specification Low CaliperMat Properties Minimum Target Maximum Pilot Mat Basis weight (lb/100 1.71.8 1.9 1.82 sq. ft) MD Tensile (lb_(f))¹ 60 85 129 CD Tensile (lb_(f))¹30 45 59 MD Rentention (%) 55 75 90 85 Loss on Ignition 17 19.5 25 19.1(LOI) Thickness⁴ (0.001″) 30 34 38 15.7

Measurements are also carried out on the mat smoothness. Tensilemeasurements are taken based on a test procedure put forward by AmericanRoofing Manufacturer Association, test method 4-82 relative tensilestrength. The test is modified for glass mat as an industry standardfrom an original 2″ width of test strip to 3″ width. All tensile valuesare pounds per three inches. Trial mats made via Rotocure (labelled“Rotocured”) and a flatbed (labelled “Flat bed cured”) are made using anassembly of glass fibers having a 16 micron fiber diameter. Incomparison to the Rotocure, the flatbed uses two parallel steel belts todimensionally constrain the glass mat. Surface smoothness is measuredand comparison is made to benchmark conventional glass mat (labelled“Conventional production mat”), and an ultra-smooth mat (labelled “11micron fiber GM”), both cured without dimensional constraint. FIG. 10illustrates the differences made by the compressed curing process on thesmoothness of the glass mat.

From the figure, it is evident that the dimensionally constrained curingprocess is able to reduce the surface roughness of the glass mat, givingit a much improved feel-to-touch for a facer application. Thedimensionally constrained glass mat from Flat bed cured and Rotocuredprocesses produces a surface smoothness in between the originalConventional production Mat 16 micron M fiber product and the 11 micronH fiber product, thus leaving it close to the smoothness resultsachievable for a 13 micron K fiber product. Accordingly, thedimensionally constrained glass mats have a surface smoothness less thanthe Conventional production Mat made with an equivalent fiber diametersize. It is also surmised that a glass mat having an assembly of glassfibers with a larger micron fiber diameter size, such as 16 microns asshown above, that is cured under dimensional constraint will have asurface roughness equivalent or even less than a glass mat with anassembly of glass fibers having a smaller micron fiber diameter sizecured without dimensional constraint. Notably, lower diameter fibers aretypically more expensive, thus the use of high diameter fiber is morecost effective.

Example 4

A standard urea-formaldehyde binder with 1.5% acrylic latex is appliedto a wet laid glass mat via a wet laid process at a solid content of 15%by dilution with whitewater. The glass mats are 10 inch by 10 inchsheets that include an assembly of glass fibers having a diameter ofabout 16 microns. All the mats are dried in a convection oven at 60° C.for 5 minutes to drive off water prior to curing. Cure conditions can beseen in Table 3.

TABLE 3 Cure conditions Name Press Process Curing 0 psi control NoneConvection, 180 C., 3 minutes 0.05 psi pre Cold copper platesConvection, 180 C., 3 minutes 0.05 psi post-P Cold copper platesConvection, 180 C., 3 minutes 30 psi pre Cold carver press withConvection, 180 C., PTFE liner 3 minutes 30 psi post-P Cold carver presswith Convection, 180 C., PTFE liner 3 minutes 60 psi pre Cold carverpress with Convection, 180 C., PTFE liner 3 minutes 60 psi post-P Coldcarver press with Convection, 180 C., PTFE liner 3 minutes 0.05 psi CCCopper plates in oven 180 C., 12 minutes (cold plates) 1 psi CC Dualbelt press 210 C., 20 seconds laminator

A number of glass mats cured under dimensional constraint (labelled as“CC” and compared to glass mats cured without dimensional constraint buteither pre-pressed prior to cure (“pre”) or post-pressed after cure(“post-P”). Results can be seen in Table 4 and FIGS. 11-15 for Tensile,Caliper, Pp Flatness, Pz Flatness, and RMS Roughness with a 7.5centimeter line scan.

TABLE 4 Pressure Tensile Caliper Pp Pz RMS Name: (psi) (lbs/3″) (mils)(um) (um) (um) Control 0 77 37 610 1485 274 0.05 psi pre 0.05 104 34 4191083 168 0.05 psi post-P 0.05 89 32 462 931 182 30 psi pre 30 75 31 423861 166 30 psi post-P 30 81 29 659 1135 210 60 psi pre 60 98 37 507 1042200 60 psi post-P 60 78 30 486 1082 216 0.05 psi CC 0.05 86 26 275 688133 1 psi CC 1 108 16 212 577 100

Notably, the samples cured under compression have improved caliper,flatness (Pp and Pz) and roughness compared to the samples placed underpressure before or after cure.

Example 5

Several equivalent samples of a glass mat and standard urea-formaldehydebinder are heated at various temperatures and the caliper is measured.At 60° C., the binder in the glass mat is dried and not cured. At thehigher temperatures, the binder in the mat cures. As seen in FIG. 16,the caliper of a dried sheet is significantly lower than a curedhandsheet. FIG. 16 clearly demonstrates on how the caliper increases andexpansion of the glass mat occurs due to the cure of the binder (withoutdimensional constraint) and the formation of voids.

Certain features, for clarity, described herein in the context ofseparate embodiments, may also be provided in combination in a singleembodiment. Conversely, various features that are, for brevity,described in the context of a single embodiment, may also be providedseparately or in any subcombination. Further, reference to values statedin ranges includes each and every value within that range.

Benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any feature(s) that maycause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeature of any or all the claims.

The specification and illustrations of the embodiments described hereinare intended to provide a general understanding of the structure of thevarious embodiments. The specification and illustrations are notintended to serve as an exhaustive and comprehensive description of allof the elements and features of apparatus and systems that use thestructures or methods described herein. Separate embodiments may also beprovided in combination in a single embodiment, and conversely, variousfeatures that are, for brevity, described in the context of a singleembodiment, may also be provided separately or in any subcombination.Further, reference to values stated in ranges includes each and everyvalue within that range. Many other embodiments may be apparent toskilled artisans only after reading this specification. Otherembodiments may be used and derived from the disclosure, such that astructural substitution, logical substitution, or another change may bemade without departing from the scope of the disclosure. Accordingly,the disclosure is to be regarded as illustrative rather thanrestrictive.

What is claimed is:
 1. A glass mat comprising: an assembly of glass fibers, wherein the assembly of glass fibers are substantially randomly oriented with a tensile anisotropy of less than about 6 in any two directions; and a binder composition comprising an organic resin; wherein the glass mat has a surface roughness more than about 10% lower than an equivalent glass mat having an assembly of naturally packed glass fibers with an equivalent fiber diameter size.
 2. The glass mat of claim 1, wherein the glass mat has a comparable tensile strength compared to an equivalent glass mat having an assembly of naturally packed glass fibers with an equivalent fiber diameter size.
 3. The glass mat of claim 1, wherein the glass mat has a thickness that varies not greater than about 5% across the total width of the mat.
 4. The glass mat of claim 1, wherein the glass mat has a caliper more than about 10% lower compared to an equivalent glass mat having an assembly of naturally packed glass fibers with an equivalent fiber diameter size.
 5. The glass mat of claim 1, wherein the organic resin comprises a urea-formaldehyde composition, a latex composition, a styrene-butadiene rubber (SBR) composition, a vinyl acetate ethylene composition, a blend or combination thereof.
 6. The glass mat of claim 5, wherein the binder composition comprises the latex present at an amount of up to about 5% by weight, such as up to about 7% by weight, or even up to about 100% by weight, based on the total weight % of the binder composition.
 7. The glass mat of claim 1, wherein the binder composition is about 5% by weight to about 50% by weight of the cured glass mat.
 8. The glass mat of claim 1, wherein the assembly of fibers is a non-woven mat.
 9. The glass mat of claim 1, wherein the assembly of glass fibers comprises an A-type glass fiber, a C-type glass fiber, an E-type glass fiber, an S-type glass fiber, an E-CR-type glass fiber, a wool glass fiber, or a combination thereof.
 10. The glass mat of claim 1, further comprising a polymer film coating adjacent to a surface of the glass mat.
 11. A glass mat comprising: an assembly of glass fibers, wherein the assembly of glass fibers are substantially randomly oriented with a tensile anisotropy of less than about 6 in any two directions; and a binder composition comprising an organic resin; wherein the glass mat has a caliper more than about 10% lower than an equivalent glass mat having an assembly of naturally packed glass fibers with an equivalent fiber diameter size.
 12. The glass mat of claim 11, wherein the glass mat has a comparable tensile strength compared to an equivalent glass mat having an assembly of naturally packed glass fibers with an equivalent fiber diameter size.
 13. The glass mat of claim 11, wherein the glass mat has a thickness that varies not greater than about 5% across the total width of the mat.
 14. The glass mat of claim 11, wherein the glass mat has a surface roughness more than about 10% lower compared to an equivalent glass mat having an assembly of naturally packed glass fibers with an equivalent fiber diameter size.
 15. The glass mat of claim 11, wherein the organic resin comprises a urea-formaldehyde composition, a latex composition, a styrene-butadiene rubber (SBR) composition, a vinyl acetate ethylene composition, a blend or combination thereof.
 16. The glass mat of claim 15, wherein the binder composition comprises the latex present at an amount of up to about 5% by weight, such as up to about 7% by weight, or even up to about 100% by weight, based on the total weight % of the binder composition.
 17. The glass mat of claim 11, wherein the binder composition is about 5% by weight to about 50% by weight of the cured glass mat.
 18. The glass mat of claim 11, wherein the assembly of fibers is a non-woven mat.
 19. The glass mat of claim 11, wherein the assembly of glass fibers comprises an A-type glass fiber, a C-type glass fiber, an E-type glass fiber, an S-type glass fiber, an E-CR-type glass fiber, a wool glass fiber, or a combination thereof.
 20. The glass mat of claim 11, further comprising a polymer film coating adjacent to a surface of the glass mat. 